This invention relates to telephony and in particular relates to a fault isolation device for determining whether a fault occurring in a telephone system lies with the local telephone company or in customer-owned telephone equipment.
In conventional customer-owned PBX and KSU systems, there is no provision for isolating the telephone company trunks from the customer-owned equipment, and thus, there is no easy way that the customer can determine whether the problem lies in his equipment or with the phone company.